Merge pull request #3952 from tarleb/lua-pipe-wrapper

Lua pipe wrapper

1 files changed, 24 insertions, 1 deletions

diff --git a/data/pandoc.lua b/data/pandoc.lua
index bce4e9326..fc83103e0 100644
--- a/data/pandoc.lua
+++ b/data/pandoc.lua
@@ -782,7 +782,7 @@ M.UpperAlpha = "UpperAlpha"
 -- assert(block.content[1].t == "Emph")
 function M.read(markup, format)
   format = format or "markdown"
-  local pd = pandoc.__read(format, markup)
+  local pd = pandoc._read(format, markup)
   if type(pd) == "string" then
     error(pd)
   else
@@ -790,6 +790,29 @@ function M.read(markup, format)
   end
 end
 
+--- Runs command with arguments, passing it some input, and returns the output.
+-- @treturn string Output of command.
+-- @usage
+-- local ec, output = pandoc.pipe("sed", {"-e","s/a/b/"}, "abc")
+function M.pipe (command, args, input)
+  local ec, output = pandoc._pipe(command, args, input)
+  if ec ~= 0 then
+    err = setmetatable(
+      { command = command, error_code = ec, output = output},
+      { __tostring = function(e)
+          return "Error running " .. e.command
+            .. " (error code " .. e.error_code .. "): "
+            .. e.output
+        end
+      }
+    )
+    -- TODO: drop the wrapping call to `tostring` as soon as hslua supports
+    -- non-string error objects.
+    error(tostring(err))
+  end
+  return output
+end
+
 --- Use functions defined in the global namespace to create a pandoc filter.
 -- All globally defined functions which have names of pandoc elements are
 -- collected into a new table.